In some states, you may need a certificate of having taken the courses in education to teach -- or schools need a certain percentage of their faculty to be prepared in education, etc. You'll have to check with the schools in your area and/or your state board as to the laws in your state and the preferences of your local possible employers.
Just because you may be a true expert in a clinical field does not mean you know anything about teaching -- and some schools and some states are starting to insist that faculty be knowledgable about education as well as clinical.
I can only speak for my state/area as far as obtaining a job. In NY (city and Long Island area), a masters in nursing is sufficient. More than half of my colleagues are NPs. As far as preparation, it all depends. I think NPs tend to have a clinical advantage over educators, especially if they have practiced as an NP (it's a generalization, not a fact). I feel less clinically competent than them (but maybe that's just me). I feel that the masters in Ed better prepared me to teach, as far as curriculum construction, evaluations, teaching strategies and test prep (ESP having had to take statistics and a whole class on item analysis and test construction). That's not to say that a non education major cannot pick this up along the way, especially of your faculty are supportive.
As far as NLNAC goes, their biggest concern is that your masters is in nursing. I know that sounds like a no-brainier, but some nurses choose not go get their masters in nursing (or have a masters in something else before they become a nurse, and don't want to take the time to get a second masters). It becomes a major issue for accreditation, and a potential employer may not feel you are worth it.
I am nearing completion of a masters in nursing education and am already looking into the doctorate. Why? Check out the qualifications of nursing faculty jobs posted. Yes some are satisfied with a masters but more than not they require a doctorate or at least working on one or a PhD. Go to The Chronicle and see for yourself. This is an excellent site for finding jobs. I encourage you to work towards your terminal degree. Do a little at a time (look into tuition reimbursement). Good Luck
It helps a LOT to be really clinically strong and up-to-date; that gains you the respect of the students and of the staff at clinical agencies. But, it may not be enough, especially if you want to be a truly excellent educator. Education is a different area, and deserves lots of respect too. Some of us who do not have training in nursing education do catch on, or learn as we go form peers, mentors, by attending conferences, or from just reflecting on our own past experiences as learners. You may also have been a preceptor to nurses in the past, which gives you the perspective that different people learn in different ways.
If you have a chance, take a course or two on active learning strategies, on test development and analysis, etc. Learning how to write good, accurate exams is a real challenge--it is NOT something you can pick up on the job easily, and it is not fair or your students to practice on them as you get the hang of it. Attend QSEN, so you will be up-to-date, and realize that what we teaches nurses needs to shift so that they can become key members of a HC system that focuses on high quality, safe, effective, culturally sensitive, patient-centered care. Read the report on The Future of Nursing, and Benner's book, Educating Nurses. Nurisng education is going through some major changes right now, so prepare yourself to teach nursing in different ways and with a different focus than in the past.
Because you have content knowledge (in nursing) does not necessarily mean you have pedagogical knowledge (how to teach), let alone pedagogical content knowledge (how to teach nursing). Education courses are very important.